If you add an event and set it to all day the event appears on the day before, and if you have fullcalendar enabled, also the day you chose.
This is likely to be to do with timezones, my tests are with the server (php), the tiki pref and the user all being in UTC. Will try to reproduce on show.
Hmm, maybe just a UTC thing then - http://jonnybradley-8515-4996.show.tikiwiki.org/tiki-calendar.php looks fine with me in UTC and the server in UTC+1 - i hate timezones!
Aha, but if i set my local to UTC+1 i get the event spanning two days, ok might be able to fix it myself now...
Workaround: Setting the event to one day (will span it 2 days) then drag back to one day work. Bernard Sfez / Tiki Specialist